Information is pretty scarce on getting these up and running, so I hope this quick guide might help to clarify the process for others.
First, you want to expand the filesystem. Launch raspi-config:
Go to Advanced -> Expand filesystem
Now you’ll need a copy of the driver. Download it here.
cd Downloads && tar xvf LCD-show-*.tar.gz cd LCD-show/ chmod +x LCD35-show ./LCD35-show
This installs the driver and also makes the LCD screen the default choice.
This means your HDMI screen will not display your desktop any longer on boot.
To make HDMI the default choice again, cd to your LCD-show folder and run the following:
Naturally you can run the following again to switch back to the screen.